A refrigerator is a product designed to keep an internal temperature thereof at a predetermined temperature or lower for the purpose of fresh storage of food. Therefore, in order to keep cold air generated in an inside of the refrigerator and prevent heat outside the refrigerator from permeating into the inside of the refrigerator, an insulation layer is formed between an inner case and an outer case of the refrigerator during manufacture of the refrigerator. The insulation layer is generally formed by filling foaming liquid between the inner case and the outer case and hardening the foaming liquid. An inside of a microcell of a polyurethane insulation layer is filled with carbon dioxide gas and foaming agent gas generated by vaporization due to high heat during reaction. However, CFC, HCFC and cyclopentane, or the foaming agent gas, and the carbon dioxide has high thermal conductivity, which causes deterioration in insulation property of the polyurethane insulation layer. Therefore, a vacuum insulation panel having high insulation property is used to supplement the insulation effect of the aforementioned polyurethane insulation layer. In general, a vacuum insulation panel having a predetermined size is inserted between the inner case and the outer case of the refrigerator and conventional polyurethane foam is filled around the vacuum insulation panel.
The vacuum insulation panel is an insulation panel, in which foamed resin or fiber material is put as a core material into a surface material, and has a considerably reduced thermal conductivity of a gas by keeping an inside of the insulation panel in vacuum. In order to keep the insulation performance of the vacuum insulation panel for a long period, it is necessary to continuously keep the inside of the insulation panel in vacuum. However, when a pinhole is generated in the surface material during manufacture of the vacuum insulation panel or sealing of a thermal bonding layer is loosened with time, gas or moisture permeates into the inside of the vacuum insulation layer to lower a degree of vacuum. Therefore, to prevent the deterioration of the insulation performance, inclusion of an absorbent such as silica gel, calcium oxide and zeolite has been suggested.
This absorbent is generally placed above the core material or between the core materials, or placed in a securing part made by cutting some portion of the core material, and in this case, there has been a problem that smoothness or the insulation performance is deteriorated.